The present invention relates to methods of forming electrochemical heat sources, and in particular to electrochemical heat sources to heat tobacco to produce a tobacco flavor or tobacco-flavored aerosol.
The electrochemical heat sources of the present invention are particularly adapted for use in smoking articles that are capable of providing the user with the pleasures of smoking (e.g., smoking taste, feel, satisfaction, and the like), without burning tobacco or any other material, without producing sidestream smoke or odor, and without producing combustion products such as carbon monoxide. As used herein, the term "smoking article" includes cigarettes, cigars, pipes, and the like, which use tobacco in various forms.
Many smoking articles have been proposed through the years as improvements upon, or alternatives to, smoking products which burn tobacco.
Many tobacco substitute smoking materials have been proposed, and a substantial listing of such materials can be found in U.S. Pat. No. 4,079,742 to Rainer et al. Tobacco substitute smoking materials having the tradenames Cytrel and NSM were introduced in Europe during the 1970's as partial tobacco replacements, but did not realize any long-term commercial success
Numerous references have proposed smoking articles which generate flavored vapor and/or visible aerosol. Most of such articles have employed a combustible fuel source to provide an aerosol and/or to heat an aerosol forming substance. See, for example, the background art cited in U.S. Pat. No. 4,714,082 to Banerjee et al.
However, despite decades of interest and effort, no one had successfully developed a smoking article which provided the sensations associated with cigarette or pipe smoking, without delivering considerable quantities of incomplete combustion and pyrolysis products.
Recently, however, in U.S. Pat. Nos. 4,708,151 to Shelar, 4,714,082 to Banerjee et al., 4,756,318 to Clearman et al. and 4,793,365 to Sensabaugh et al., there are described smoking articles which are capable of providing the sensations associated with cigarette and pipe smoking, without burning tobacco or delivering considerable quantities of incomplete combustion products. Such articles rely on the combustion of a fuel element for heat generation, resulting in the production of some combustion products.
Over the years, there have been proposed numerous smoking products which utilize various forms of energy to vaporize or heat tobacco, or attempt to provide the sensations of cigarette or pipe smoking without burning any substance. For example, U.S. Pat. No. 2,104,266 to McCormick proposed an article having a pipe bowl or cigarette holder which included an electrical resistance coil. Prior to use of the article, the pipe bowl was filled with tobacco or the holder was fitted with a cigarette. Current was then passed through the resistance coil. Heat produced by the resistance coil was transmitted to the tobacco in the bowl or holder, resulting in the volatilization of various ingredients from the tobacco.
U.S. Pat. No. 3,258,015 and Australian Patent No. 276,250 to Ellis et al. proposed, among other embodiments, a smoking article having cut or shredded tobacco mixed with a pyrophorous material such as finely divided aluminum hydride, boron hydride, calcium oxide or fully activated molecular sieves. In use, the pyrophorous material generates heat which reportedly heated the tobacco to a temperature between 200.degree. C. and 400.degree. C. to cause the tobacco to release volatilizable materials. Ellis et al. also proposed a smoking article including cut or shredded tobacco separated from a sealed pyrophorous material such as finely divided metallic particles. In use, the metallic particles were exposed to air to generate heat which reportedly heated the tobacco to a temperature between 200.degree. C. and 400.degree. C. to release aerosol forming materials from the tobacco.
PCT Publication No. WO 86/02528 to Nilsson et al. proposed an article similar to that described by McCormick. Nilsson et al. proposed an article for releasing volatiles from a tobacco material which had been treated with an aqueous solution of sodium carbonate. The article resembled a cigarette holder and reportedly included a battery operated heating coil to heat an untipped cigarette inserted therein. Air drawn through the device reportedly was subjected to elevated temperatures below the combustion temperature of tobacco and reportedly liberated tobacco flavors from the treated tobacco contained therein. Nilsson et al. also proposed an alternate source of heat whereby two liquids were mixed to produce heat.
Despite many years of interest and effort, none of the foregoing non-combustion articles has ever realized any significant commercial success, and it is believed that none has ever been widely marketed. Moreover, it is believed that none of the foregoing non-combustion articles is capable of adequately providing the user with many of the pleasures of cigarette or pipe smoking.
Thus, it would be desirable to produce a heat source that can be used to construct a smoking article which can provide many of the pleasures of cigarette or pipe smoking, which does not burn tobacco or other material, and which does not produce any combustion products.